In the hub world "Crossroads of the World", you can head to the upper left, up the light alignment elevator. The zone entrance up there is to the other Origin levels. If you look at the map posted for Crossroads in this thread, it's the zone entrance directly to the left of the "player here" marker (and the only zone entrance on the map because I took the photo when you first make it there).

Sigh, my 2 were in the Origin levels as well, all that time traipsing through the game for nothing